install from usb key? (Slightly OT)

[Furnish, Trever G]

I have an 8GB usb key.  I'd like to be able to do an automated install
of RHEL4 from it.  But I'd also like to boot other ISOs from it as well.
Anyone have any ideas or pointers even for where to start looking for
info on doing that?
 
Note, I already know how to build a custom kickstart CD -- that's not
what I need help with.
 
I'm looking for a way to put multiple, completely unrelated ISO images
on a single USB key and then have a boot-loader that lets me choose
between them, then boot from them as though the CD was in the drive.
 
For example, here are possible ISO images and floppy disk images I would
like to store on the USB key and boot from:
 
- custom kickstart iso image to do an automated install of redhat
- per-server boot floppy image (as produced using mkbootdisk)
- SystemRescueCD iso image (http://www.sysresccd.org)
- msdos floppy disk image to boot memtestx86
- "Ultimate Bood CD for Windows" (http://www.ubcd4win.com)
 
So basicly I need some way to select from among multiple boot sectors
(grub would probably be fine) and some way to determine those boot
sectors (this is where i'm lost).
 
Any ideas?